الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The current study was performed on postpartum cows of Holstein breed after application of estrus synchronization protocols before insemination by frozen semen obtained by different sires to determine the effectiveness of presynch and ovsynch protocols compared with spontaneously heated cows on reproductive performance. And measure the effect of sire on reproductive performance of postpartum cows under study. Beside detecting the effect of parity, age, days open, milk yield and body condition score of cows under study on the reproductive performance.
- A total number of 643 postpartum lactating cows (1-8 parity), (2-12 years old), (60-290 days open), (10-40 kg/day milk yield) and (2.5-4.5 BCS) were used over the periods from March 2016 till March 2017.
- All cows were exposed to rectal and vaginal palpation to verify the normal post parturient uterine involution and normal ovarian structure.